1. Field of the Invention
The present invention relates to a gantry type hybrid parallel linkage 5-axis machine tool, in particular, to a high efficiency machine tool having at least five dimensional axis moving directions composed of a parallel spatial linkage mechanism and a gantry type framework.
2. Description of the Prior Art
In bygone time, the conventional gantry type 5-axis machine tools are all in a form of serially linked feeding mechanism in which a linear feeding shaft and a rotating shaft are laid overlapping. Referring to FIGS. 1(A) and 1(B), wherein FIG. 1(A) is a gantry type 5-axis machine tool presently in mass production by PARPAS Co., and FIG. 1(B) shows its main shaft head in possession of two independently rotatable directions(A/C axes rotational direction). This type of machine tool is the most commonly adopted gantry type 5-axis machine tool. In this machine tool, the X axis feeding control is carried out by movement of a main shaft head base along a transverse beam; the Y axis feeding control is carried out by movement of the transverse beam along a U shaped structure; While the Z axis feeding control is carried out by movement of the head base. As for the directional adjustment of the A/C axis is controlled by the rotatable main shaft head shown in FIG. 1(B). Hence, the scheme of the gantry type 5-axis machine tool shown in FIG. 1(A) is basically a serially banked mechanism with rigidity like a serially jointed spring. In case there is a component with insufficient rigidity, the rigidity of the whole serial system will be degraded.
Fatal shortcomings of such a serial mechanism exist in its excessive cantilever length that brings about too long of loading path, less rigidity, susceptible to yielding to bending moment, and the thermally non-symmetric structure which often causes restriction to system dynamic frequency range disadvantageous to high speed operation. Putting the structure in a rough finish condition is a usual remedy of solving the problem. However, the machine constructed as such requires greater driving force to activate the feeding mechanism resulting in greater power consumption and increasing production cost. At present, notwithstanding the geometrical errors in machine dimensions and the thermal deformation etc. can be compensated through computer numerical control (CNC) technology so as to upgrade the machine accuracy for a serially constructed machine tool with such a less costly computer software, it is a primary consideration that whether the machine is of sufficient repeatability, (i.e., having sufficient rigidity and resistive to low thermal deformation). It is regretful that the present serially constructed machine tools are far from these features.
Meanwhile, it is that one which having a main shaft head composed of two rotational axes has the lowest rigidity yet the highest production cost among the conventional gantry type 5-axis machine tools that causes the serial feeding mechanism applied therefore to suffer from insufficient rigidity and difficulty in high speed operation. Moreover, users have to tolerate a high market price for this type of machine tools. It is therefore the utmost important matter to improve the rigidity of the main shaft head of the above described 5-axis machine tool and reduce its production cost so as to promote the domestic and even the international market growth for the gantry type 5-axis machine tool.
Aiming at the above depicted problems, the present invention is to propose an ingeniously developed construction for a gantry type hybrid parallel linkage five-axis machine tool capable of operating with a satisfactory rigidity, high speed, and less thermal deformation.
Therefore, it is an object of the present invention to provide a gantry type hybrid parallel linkage 5-axis machine tool wherein by combining the parallel spatial linkage with all types of gantry machine tool so as to palliate the aforesaid defects of the conventional gantry type multi-axis serial machine tools such as long loading path caused by a too long cantilever arm, insufficient rigidity, susceptible to deformation by bending moment, and thermally non-symmetric structure.
It is another object of the present invention to provide a gantry type hybrid parallel linkage 5-axis machine tool with a simple structure easy for assembling yet having a high rigidity and a low inertia suitable for high speed feeding operation thereby upgrading the machine accuracy and widening the system dynamic frequency region.
For achieving aforesaid objects, the gist of the present invention is to apply my xe2x80x9cHybrid structural Multi-Axis machine Toolxe2x80x9d disclose in Patent Gazette No. 363480 Taiwan ROC, and xe2x80x9cComposite Mechanism Multi-Axis Machine Toolxe2x80x9d disclosed in U.S. Pat. No. 6,048,143, for all types of gantry structural machine tool so as to improve the operation speed of the feeding mechanism of the gantry type machine tool well utilizing the high rigidity and the low inertia features of a parallel spatial linkage mechanism.
The present invention essentially comprises: A pedestal with at least two parallel linear guide ways provided at its one surface thereof; and a working platform with two sliding slots provide at its surface facing to the pedestal such that the working platform may move straightly with respect to the pedestal by coupling the two sliding slots with the two linear guide ways. A machine framework is at least composed of a planar roof and two supporting columns, the end portions of the columns are parallelly fixed to both sides of the pedestal, and the surfaces of the other two end portions are each provided with a linear guide way. Besides, a sliding slot is formed at each side of the planar roof such that the planar roof is able to make straight linear motion with respect to the columns by coupling the two sliding slots with the two linear guide ways on the end portion s of the columns. A hollow guide hood is secured its one end to one side of the planar roof, and the other end extending towards the pedestal. A parallel spatial linkage mechanism formed of a plurality of straight feeding molding dies are parallelly in connection with a base in the way that the individual molding die is able to swivel freely, and that each molding die is connected with the base in an indivisual position. By so the base is able to make at least two dimensional swiveling driven by those straight feeding molding dies. Each straight feeding molding die includes a linear guide way, a sliding base, and a connecting rod, the sliding base can move linearly along the linear guide way, the connecting rod can at least make an uni-dimensional swiveling with its one end hinged to the sliding base in the version that forming a hinge pin at the rod side while forming a corresponding bearing on the sliding base side such that the other end of the connecting rod is able to make uni-dimensional swiveling with respect to the joint on the sliding base as a fulcrum. Besides, the opposite end of the connecting rod may be rotatably hinged to the sliding base with a universal shaft coupling or a ball joint. With this structure the sliding base is able to make at least uni-dimensional displacement and two dimensional swiveling thus altogether three dimensional movement is possible. A refining molding unit is installed on a side surface of the Pedestal facing to the working platform. The refining molding unit is a cutting equipment having cutting tools Provided at its one end thereof capable of cutting and refining a work piece gripped on the working platform. Besides, this refining molding unit may also be a welding or supersonic bonding equipment. A feeding shaft mechanism is for driving above mentioned planar roof to make uni-dimensional movement along the linear guide ways. A controller is for controlling and coordinating the operation of parallel spatial linkage mechanism with the feeding shaft mechanism, and adjusting the relative position between the refining molding unit and the working platform.
Meanwhile, in the present invention, the aspect of assembling the pedestal, the working platform, the machine framework and the guide hood can be varied in many respect for matching with the parallel spatial linkage so as to serve effectively as a parallel spatial linkage mechanism. If the working platform is secured to one surface of the pedestal, and one end portion of each column is parallelly fixed to each side of the pedestal respectively, whereas the other end portion of each column is provided with a linear guide way which is able to match its own corresponding linear guide way so as to enable the planar roof to make uni-dimensional movement (Y axis direction). And, other two linear guide ways are formed on the other end surfaces of both columns. The former two linear guide ways and the latter two linear guide ways respectively make their projections on X ais and Y axis planes perpendicular to each other thereby guiding hood is able to make uni-dimensional movement (X axis direction) by the two sliding slots formed on it to slide on the two linear guide ways provided on the planar roof. And, further modification is possible with the structure that the two linear guide ways formed on the pedestal facing to ∩ shaped machine framework and the two linear guide ways formed on the planar roof make projection on the XY axis planes perpendicular to each other such that the working platform is able to make uni-dimensional movement in X axis direction by coupling the two sliding slots formed on the bottom of the working platform with the two linear guide ways formed on the pedestal.